INTEGRATED SYSTEMS ANALYSIS OF THE GUT MICROBIOTA PHENOTYPES IN THE RHEUMATOID ARTHRITIS
Authors: J. Qiao et al.
Research on the intestinal microbiota of rheumatoid arthritis (RA) patients has described various deviations in bacterial species and functional composition («dysbiosis»). The type of intestinal dysbiosis associated with RA has been inconsistent and difficult to characterize, probably owing to differing patient populations, variable disease stages (established RA, early RA), multiple underlying immunosuppressive treatments and certainly the complexity of microbiota analysis.
The authors of this work have analyzed the intestinal microbiota of 145 Chinese RA patients, and instead of describing the relative proportion of specific intestinal bacteria, they searched for robust clusters (referred to as enterotypes), using machine learning techniques. The authors identified two predominant patterns of dysbiosis. These «RA-enterotypes» have distinct bacterial distribution, one primarily dominated by Prevotella, the other by Bacteroides. Interestingly, these intestinal «RA-enterotypes» were associated with different levels of inflammatory biomarkers (ESR, CRP), of autoantibodies (ACPA), and other biomarkers.
Microbiota variations are stratified (grouped into enterotypes), not continuous, which suggests the existence of a limited number of stable host-microbial symbiotic states. It is not surprising that these enterotypes are associated with different forms of immune response. While the authors show some (weak) correlations with clinical markers, these associations cannot be considered as causal. For that, longitudinal studies of the intestinal microbiome are needed, preferentially in early untreated RA. The question of real clinical relevance is whether RA-enterotypes respond differently to antirheumatic drugs or differ in their long-term prognosis. If this was the case, the assessment of our intestinal microbiota would become part of a personalized medicine approach in RA.